Can a F-1 students out of status for more than 6 month but still in school apply for reinstatement ?

Reinstatement is restricted to students who have been out of status for no more than five months. Probably the best way for you to find out what your status is would be to make an infopass appointment at the local field office of USCIS. Failing that, you could always attempt to obtain information on your immigration history through requesting a copy of your file under the Freedom of Information Act. Quite possibly your reinstatement failed and the SEVIS system shows that you are not in legal status. But that is not a certainty. A problem with leaving the US if the reinstatement request failed is that you would have received a formal adjudication from USCIS. If the answer was negative, the time for unlawful presence which would bar you from returning to the US begins to run from the date of denial. So it is highly advisable for you to obtain a clear picture of your immigration history through infopass or Freedom of Information Act before taking further actions, especially to leave the country. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.

You can try to reapply for reinstatement.  It will turn on your explanation of why you fell out of status.